How can you print off pictures when the pictures are just saved on your laptop?

I have several pictures saved on my laptop that I imported from other peoples memory cards. Problem is I have to go to a photo center to print them off. I want to know what device can I put my pictures on so I can get them printed off. I tried saving them on a flash drive and either that doesn’t work or I just don’t know how to do it properly. Can anyone tell me what I can put them on and how to do it and remember I am not a computer expert so if you could speak with simple words and very slowly it would help me greatly! Thanks :)